Is it not possible to supply a thread facory or name pattern to ForkJoinPool?

Question

I would like to set name for threads of the ForkJoinPool used by work stealing pool, supplied by

ExecutorService newWorkStealingPool(int parallelism)

or

ExecutorService newWorkStealingPool()

So far I could not find a way to set custom names on threads used by this ExecutorService, is there a way?

newWorkStealingPool() basically supplies a ForkJoinPool, but ForkJoinPool also doesn't have a public constructor with supplied name pattern.

update: I have now found this constructor of ForkJoinPool which takes a thread factory ForkJoinPool.ForkJoinWorkerThreadFactory. But factory should return a ForkJoinWorkerThread, which doesn't have a public constructor. So I guess I will have to subclass ForkJoinWorkerThread.

Answer 1

This seems to be the minimum required code, reusing the existing default factory:

final ForkJoinWorkerThreadFactory factory = new ForkJoinWorkerThreadFactory() {
  @Override         
  public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
    final ForkJoinWorkerThread worker = ForkJoinPool.defaultForkJoinWorkerThreadFactory.newThread(pool);
    worker.setName("my-thread-prefix-name-" + worker.getPoolIndex());
    return worker;
  }
};
        
final ForkJoinPool forkJoinPool = new ForkJoinPool(Runtime.getRuntime().availableProcessors(), factory, null, false);

Update for later JDK versions:

final AtomicInteger index = new AtomicInteger();
final ForkJoinPool.ForkJoinWorkerThreadFactory factory = pool -> {
  final ForkJoinWorkerThread worker = ForkJoinPool.defaultForkJoinWorkerThreadFactory.newThread(pool);
  worker.setName("my-thread-prefix-name-" + index.getAndIncrement());
  return worker;
};

final ForkJoinPool forkJoinPool = new ForkJoinPool(Runtime.getRuntime().availableProcessors(), factory, null, false);